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真空蒸镀法结合溶胶凝胶法成功地制备Cu-TiO23层复合结构薄膜。运用XRD,SEM,UV-vis等手段进行结构表征和光吸收性能测试。通过模拟可见光下制备样品对亚甲基蓝溶液降解率的变化,评定其光催化活性。结果表明:该法制备的复合结构薄膜,在未热处理时真空蒸镀的金属层为单质Cu。在723 K热处理后,沉积的Cu被氧化主要以Cu2O的形式存在,而TiO2为单一的锐钛矿晶型。823 K保温2.0 h热处理后Cu2O进一步被氧化为CuO,同时出现了少量金红石型TiO2。由于Cu2O与CuO均为窄带隙的半导体,在可见光照射下会发生电子由价带向导带的跃迁,因此复合薄膜表现出明显的可见光吸收性能。降解实验的结果则表明:不同温度热处理后的复合薄膜均表现出较高的光催化活性,特别是723 K热处理后的复合薄膜样品可见光催化活性最好,在可见光照射5.0 h后对亚甲基蓝溶液降解率接近100%。分析其原因认为,p型的Cu2O和CuO与n型TiO2半导体接触后,在其界面形成了纳米异质结的结合,其p-n结的内建电场抑制了光生载流子的再复合,提高了量子产率,因此使复合薄膜表现出较高的光催化性能。
The Cu-TiO23 composite films were successfully prepared by vacuum evaporation and sol-gel method. XRD, SEM, UV-vis and other means of structural characterization and light absorption properties of the test. The photocatalytic activity of methylene blue solution was evaluated by simulating the change of degradation rate of methylene blue solution in visible light. The results show that the composite structure of the film prepared by this method, when not heat-treated vacuum-deposited metal layer as a single element of Cu. After 723 K heat treatment, the deposited Cu is oxidized mainly in the form of Cu2O, while TiO2 is a single anatase. 823 K Insulation 2.0 h After heat treatment, Cu2O is further oxidized to CuO while a small amount of rutile TiO2 appears. Since both Cu2O and CuO are narrow bandgap semiconductors, the transition from valence band to conduction band occurs under the irradiation of visible light, so the composite film shows obvious visible light absorption performance. The results of the degradation experiments showed that the composite films after heat treatment at different temperatures showed high photocatalytic activity, especially the composite films after 723 K heat treatment had the best photocatalytic activity. The degradation of methylene blue solution was observed after 5.0 h of visible light irradiation Rate close to 100%. The reason is that the contact of p-type Cu2O and CuO with n-type TiO2 semiconductor forms a combination of nano-heterojunctions at the interface, and the built-in electric field of pn junction suppresses the recombination of photogenerated carriers, Quantum yield, so composite films show higher photocatalytic properties.